EFFECT OF DRUGS INFLUENCING CENTRAL SEROTONERGIC MECHANISMS ON METHAMPHETAMINE-INDUCED STEREOTYPED BEHAVIOR IN THE RAT

Pretreatment with L-tryptophan, a precursor of serotonin, decreases the intensity of stereotyped behavior induced by methamphetamine, while methysergide, a serotonin antagonist, increases the intensity of methamphetamine-induced stereotyped behavior. Apparently the intensity of methamphetamine-induced stereotypy depends on the balance between central dopaminergic and serotonergic systems, and the central serotonergic system may have an opposing, tonic effect on central dopaminergic systems involved in the mediation of stereotypy. Pretreatment with quipazine, a serotonin agonist, and clomipramine, a selective serotonin neuronal uptake blocker, potentiates the stereotyped behavior induced by methamphetamine. The probable mechanisms by which quipazine and clomipramine might have potentiated the methamphetamine-induced stereotypy are discussed.